Investigating Clues that Crawl, Squirm, and Fly
Scientists use maggots, beetles, and termites as insect evidence to crack a case.
Published July 10, 2006
By Adelle Caravanos
It’s the stuff of horror movies. As a dead body rots, maggots take up residence in the open cavity of the mouth. Flies swarm over the corpse, feeding on the decaying flesh. Eventually, mites and roundworms begin to make a home out of what’s left of the tissue.
The thought of these skin crawling creatures is enough to, well, make your skin crawl.
But for a few scientists — forensic entomologists — this is an everyday scene. The insects are creeping clues that can shed light on mysterious crimes. At CSI: Crime Scene Insects, a new interactive exhibit at the New York Hall of Science, kids experience first-hand how and what these insect investigators learn from the tiniest of witnesses.
The exhibit, inspired by the popular CSI: Crime Scene Investigation television series, explores the field of forensic entomology, in which scientists use the insects discovered at a crime scene to determine time of death and other important details of the case. CSI: Crime Scene Insects features live maggots, flies, dermestid or flesh-eating beetles, and other insects; crime scenes and evidence collection equipment; a staged morgue with two plastic cadavers at different stages of decay; and a section of a courtroom where kids learn how evidence is presented to juries. The exhibit covers several areas of forensic science, including:
History
Forensic entomology first emerged in 13th-century China, when Sung Tz’u wrote The Washing Away of Wrongs. A man had been killed with a sickle, and the local investigator instructed the men of the town each to bring their tool for inspection. Although it had been cleaned, one sickle attracted flies — evidence of tiny remains of human flesh — and soon after, the owner confessed.
Insect Life Cycles
The types of insects present on a corpse, as well as the stage of life they are in, give important clues as to how long a body has been deceased. Maggots (fly larvae) tend to form early on a body, thriving in body cavities such as the mouth. Skin beetles, on the other hand, eat dried flesh, so they appear later.
A highlight of this area of the exhibit is the stereoscopic sculpture that depicts the life cycle of a fly, from a tiny, wormlike maggot to the adult fly stage. As the sculpture spins, it is lit by a flashing strobe light that makes the insects appear to move.
Stages of Death
Mortuary drawers reveal models of cadavers in two stages of decay. During the first stage, the body becomes bloated by gas trapped inside. The activity of maggots and other insects raises the temperature of the body (as high as 53 °C, or 137 °F) and the gases expand until the pressure causes the skin to burst. The body then enters the decay stage, and becomes a host to many other dermestid insects.
Environmental Conditions
One of the biggest challenges for a forensic scientist is determining the effects of the environment (both internal and external) on the case at hand. Entomologists use various tools to determine conditions that the body has been subject to, in particular air temperature and humidity. An interactive computer simulation allows kids to alter the external conditions and see the resulting insect population. Insects also provide clues as to the internal conditions of the body, especially levels of chemicals in a person’s system. For example, maggots develop more rapidly on tissue containing cocaine, so a level of rapid decomposition could be a clue to the presence of the drug.
Methodology & Research
The exhibit also shows the methods that forensic entomologists use to collect, interpret, and present evidence. Kids can view collection jars and look through a microscope at insect evidence; wipe-off marker boards show the breakdown of a case; and in the mock courtroom, a video explains the use of entomological evidence in legal cases.
CSI: Crime Scene Insects demonstrates the important role that insects — and the forensic entomologists who study them — play in assembling the many pieces of a case. Kids work their way through the methods and science of solving cases, and the exhibit serves as an excellent demonstration of the scientific method in action.
